A simple preparative-scale countercurrent chromatographic scheme was introduced. The scheme uses a helical column slowly rotating in the gravitational field while solvent is eluted through the column by means of rotating seals. Introduction of a two-phase solvent system in the rotating column distributes each phase to occupy nearly half the volume of every turn of the column. Consequently, elution of either phase through the column results in a high efficiency partition process of solutes between the two phases while the eluate is continuously monitored and fractionated. Using a short column, optimum operational conditions were investigated with respect to the column angle, rotational speed, and flow rate for two typical two-phase solvent systems. Under the optimized conditions the capability of the scheme was demonstrated on preparative-scale separations (10 ml sample size) of DNP amino acids and peptides. BIBLIOGRAPHIC REFERENCES: Ito, Y. and Bowman, R.L: Preparative Countercurrent Chromatography with a slowly rotating helical tube, Anal. Biochem. 78: 506-512, 1977. Ito, Y. and Bowman, R.L.: Preparative Countercurrent Chromatography with a slowly rotating helical tube. J. Chromatogr. 136: 189-198 1977.